I mentioned earlier in this thread that I expected that they would go for a tied arch here and it seems they will. The dual cable stayed spans is an expensive and excessive option for such a short span and not likely to make it past initial proposals (though it would be beautiful). Tied arches are relatively cheap, easy to install, and are the go to span these days for basically anything in the 75-250 meter range. Its telling that the old john greenleaf whittier bridge, which was a miniature copy of the bourne and sagamore bridges, was replaced with two network tied arch bridges. It would be pretty cool though if the bourne bridge was replaced with tied arches and the sagamore with cable stayed bridges, but I dont think that would happen. Would be iconic though.
Using network tied arches over the canal would mean keeping the historic arch bridge silhouette over the canal, while using modern techniques, this is definitely a win win. Plus the bridges could be built in full off site and then floated up the canal and lifted into place. There is also no need for heavy or complex anchors on either side because the tie holds the ends of the arches in tension, simplifying construction further. It definitely makes the most sense to go with tied arches here.